Efficient injection of charge carriers from the contacts into the semiconductor layer is crucial for achieving high-performance organic devices. The potential drop necessary to accomplish this process yields a resistance associated with the contacts, namely the contact resistance. A large contact resistance can limit the operation of devices and even lead to inaccuracies in the extraction of the device parameters. Here, we demonstrate a simple and efficient strategy for reducing the contact resistance in organic thin-film transistors by more than an order of magnitude by creating high work function domains at the surface of the injecting electrodes to promote channels of enhanced injection. We find that the method is effective for both organic small molecule and polymer semiconductors, where we achieved a contact resistance as low as 200 Ωcm and device charge carrier mobilities as high as 20 cm2V−1s−1, independent of the applied gate voltage.
Digital Object Identifier (DOI)
The work at WFU was supported by the National Science Foundation (NSF ECCS- 1254757 and NSF DMR- 1627925). I.M. acknowledges funding from EC FP7 Project SC2 (610115), and EPSRC project EP/M005143/1. J.E.A. acknowledges NSF DMR-1627428 for support of organic semiconductor synthesis. L.J.R. acknowledges use of the D1 beam line at the Cornell High Energy Synchrotron Source supported by the National Science Foundation (NSF DMR-0225180) and NIH-NIGMS and thanks Detlef Smilgies for support with the μ GIWAXS measurements. MG acknowledges support from the North Carolina Biotechnology Center to purchase the Asylum AFM (grant 2014-IDG-1012).
The experimental data from this study are available from the corresponding author upon reasonable request.
Supplementary Information accompanies this paper at https://doi.org/10.1038/s41467-018-07388-3.
Lamport, Zachary A.; Barth, Katrina J.; Lee, Hyunsu; Gann, Eliot; Engmann, Sebastian; Chen, Hu; Guthold, Martin; McCulloch, Iain; Anthony, John E.; Richter, Lee J.; DeLongchamp, Dean M.; and Jurchescu, Oana D., "A Simple and Robust Approach to Reducing Contact Resistance in Organic Transistors" (2018). Chemistry Faculty Publications. 140.